Concrete-form



cfB. HOPKINS.

CONCRETE FORM. APPLICATION FILED NOV. 20, 1919-.

1,379,820. Patented May 31,1921.

CECIL B. HOPKINS, OF SAN FRANCISCO, CALIFORNIA.

CONCRETE-FORM.

Specification of Letters Patent.

Patented May 31, 19 21.

Application filed November 20, 1919. Serial No. 339,341.

T 0 all whom it may concern:

Be it known that I, CECIL B. HoPKINs, a citizen of the United States, and a resident of the city and county of San Francisco and State of California, have invented a new and useful Concrete-Form, of which the following is a specification.

Myinvention relates to forms for concrete arches and especially for concrete joist floors.

An object of the invention is to provide a collapsible form readily adjustable to vary the rise of the arch.

Another object of the invention is to provide a form of the character described which is adapted for use in pouring concrete joist floors having any required width of joist.

Another object of the invention is to provide improved means for securing the forms the abutment support and retaining them singly against the abutment support whilethe concrete is being poured.

Great economy of material and labor in floor construction is found in reinforced concrete floors having joists at close intervals formed integrally with the intervening slabfand spanning from girder to girder. This construction is especially valuable in long spans and in such structures as schools, hotels, warehouses and other buildings having moving" or vibrati'n loads. In the practice of my invention employ an arch form preferably of sheet steetin standard size units which conveniently may be 20 inches wide, 15 inches deep, and 30 inches long. As many units as required by the length of the span 'are'lappe d together in desired position upon the horizontal abutnient supports which rest npon the false work. The abutment supports may be placed at any desired height and the arch forms are vertically adjustable on the supports, so that both the depth of the joist and the thickness of the intervening slab are readily varied to meet the requirements of each job. I find that provision for ad jnstment to give 8, 10. 12 and 14 inch depths is suiiicient for all ordinary conditions.

Since'the arch forms lie on the outside of the abutment supports and contiguous to their lateral sides, and are secured thereto by readily removable extensible means interposed between two adjacent abutment supports, the forms can be stripped without disturbing the supporting :talsework, after the preliminary allowing the same in a few days. i i The invention possesses other features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of my invent-ion which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood that I do not limit'myself to the showing made by the said drawings and description, as I may adopt variations of the preferred form within the scope of my invention asset forth in the claim.

In the drawings, Figure l is a. vertical portion of concrete joist sectional view of a floor. The section is taken transversely of setting of the concrete,

the joists and Sl10\ s the arch forms. and

spreader bars for the abutment supports. Fig. 2 is a "vertical sectional view ofa po'rtion'jof floor and the forms, the plane of section lying parallel to the joists. The method of lapping the 'forms is'shown. Fig. is a vertical sectional view through a portion of an arch built on a modified form of abutment support. A

My invention comprises forms 2 of any desired material, shape or size, preferably, however, having the conformation shown in Fig. 1, so that the thickness of the'joists 3 is increased adjacentthe floor slab i, and the floor sla'h is "slightly thicker adjacent the joists than on the center line between the joists. Posts 5' support the transversely placed beams 6 upon which "blocks 7- rest.

forms to be reused'withretaining the forms on The abutment snpports'S are arranged upon this false work at the"required'height to give the desired depth of joist; and spaced apart the required distance, which in the present instanceis 20 inches. Witha 4 inch joist, the joists are thus spaced 24 inch centers. Where it is necessary to interrupt the regular succession of joists with one which is extra thick, as for instance, a joist run ning between columns, forms of less width After erection f the false work 5(;--T and the placing of the abutment supports 8, the arch forms 2 are placed in position and snugly retained against the lateral faces of the pieces 8 by quickly applied spreader bars which are interposed between the sides of the form and engage both the sides of the forms and the abutment support adjacent each side. The spreader bar comprises a bar 9 having flanges 10 formed at the ends. A pointed rod 11 is threaded through each flange. The pointed end is formed with a shoulder 13 adapted to engage the surface of the form 2, and a square pyramidal point l-t, adapted to pass through appropriately formed apertures 16 in the form and to bed or engage in' the wood of the support 8. As shown in Fig. 2. the edges of each form are provided with a series of apertures 16, and these are conveniently spaced 2 inches apart to permit the vertical adjustment of the forms for varying depths of joints as spoken of above. The square points of the rods bed in the abutment supports and prevent the rods from turning when the bar 9 is turned to extend the rods. \Vhen the rods are extended, the, shoulders 13 seat against the sides of the forms around the aperture and hold them snugly against the abutment supports.

ence the use. of the spreader bar, the design and function of which is related only to the width of the form which is to be spread into snug engagement with the abutment support. Hence the joist may be of any desired thickness without afl'ecting in any way the ready adjustment of the spreaders. After the preliminary setting of the concrete so that it is capable of supporting its own weightthe bars 9 are turned to release the points and permit the "forms to be stripped. They can then be used again.

Fig. 3 shows the use of a structural steel channel 19 as the abutment. support. The sides of the channel are provided with suitably lormed and spaced apertures to receive the points 14.

I claim:

In combination with spaced wooden abutmentsupports, a plurality of overlapping metallic arch forms having substantially vertical sides extending between two adjacent supports and having their sides lying against the sides of said supports. said sides being provided adjacent their ends with series ot vertically spaced apertures, the apertures on one end of one form being arranged to register with the apertures on the overlapping end of the adjacent form and holding means passed through selected registering apertures and into the wooden abutment supports and bearing against the surface of the inner form, for fixing and holding the forms in position on the abutmentstops.

In testimony whereof, I have hereunto set my hand at San Francisco, California, this 6th day of November 1919.

CECIL B. HOPKINS.

In presence of"- H. G. PROST. 

